Summary. Cadmium chloride (CdCl2) (0·1 or 1·0%) was given in the drinking water to pregnant rabbits on Days 0 to 5 of gestation. Electron microscopy of the blastocysts revealed significant changes in the lysosomes (e.g. autophagic vacuoles and residual bodies) of endodermal cells as well as those of the inner cell mass. No such changes were evident in the trophoblast.
R. Abraham, N. Ringwood and R. Mankes
R. ABRAHAM, R. MANKES, J. FULFS, L. GOLBERG and F. COULSTON
Following the insertion of copper wire into their uterine horns, rabbits were mated and cytochemical and ultrastructural observations carried out on blastocysts and on the left (control) and right (treated) horns of the pregnant uteri. The blastocysts and uterine tissue from the control horns were normal in all respects. Blastocysts obtained from the treated horns on Day 6 of gestation contained numerous membrane-bound vacuoles, identified as lysosomes by acid-phosphatase staining, that contained amorphous material in which the presence of copper was revealed by the rubeanic acid procedure. No blastocysts were recovered from treated horns after Day 6.
Significant changes were observed in lysosomes of uterine epithelial cells on Days 6 to 10 of gestation. The effects were localized to the segment of uterus containing the copper wire and involved uptake of copper, autophagy, formation of myeloid bodies and shedding of epithelial cells containing such structures into the uterine lumen.
There was evidence to suggest that the entry of copper into blastocyst lysosomes was followed by release of lysosomal enzymes, cellular autolysis and death of the affected cells. In the uterus, the toxic effects of copper appeared to be confined to the epithelial cells, whose detachment from the mucosal surface may constitute a protective mechanism. The early effect of copper on the blastocyst suggests that this is the primary site of action of the metal.
R. ABRAHAM, J. C. FULFS, L. GOLBERG and F. COULSTON
Administration of a mixed copolymer of phenylmethylcyclosiloxane to rabbits on Days 4 and 5 of pregnancy prevented implantation. Cytochemical and ultrastructural studies revealed that the macromolecular material was taken up by 6-day-old trophoblasts (but not the embryonic cells) and was sequestrated in vacuoles. The presence of acid phosphatase in some of these vacuoles identified them as belonging to the lysosomal system. Uptake into lysosomes of macromolecular material brings about degenerative changes in the trophoblast, impeding successful implantation. No evidence was observed of the changes in uterine cells that normally accompany implantation, nor was any siloxane-like material seen in lysosomes in the uterine epithelial cells or macrophages.